Abstract: The composition and content of anthocyanins in a superior strain of ‘Tarocco’ blood orange and the ordinary variety were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and differential metabolites were selected. The results indicated that a total of 33 anthocyanin-related metabolites belonging to seven classes: cyanidin, delphinidin, peonidin, pelargonidin, malyidin, petunidin and flavonoid precursors of anthocyanin synthesis were identified in the superior strain. Furthermore, the number and kinds of anthocyanin metabolites in bore and peripheral fruits from the superior strain were identical, with no differential metabolites being found between them. In contrast, 27 and 30 metabolites were detected in bore and peripheral fruits from the control variety, and nine differential metabolites including cyanidin, delphinidin, peonidin and flavonoids were identified between bore and peripheral fruits. For both the superior strain and the ordinary variety, the main anthocyanin components were cyanidin-3-O-(6-O-malonyl)-glucoside and cyanidin-3-O-glucoside, accounting for 42.3% and 41.0% of the total anthocyanin content in the inner bore fruit and 40.6% and 41.4% of the total anthocyanin content in peripheral fruit from the superior line; and accounting for 39.5% and 41.0% of the total anthocyanin content in inner bore fruit and 36.8% and 40.6% of the total anthocyanin content in peripheral fruit from the common variety, respectively. Compared with the control variety, the amount of cyanidin and the proportion of total anthocyanins in the superior strain were significantly increased, and the total cyanidin contents in inner and peripheral fruits from the superior strain were 48.68 (91.90%) and 62.16 μg/g (92.28%), respectively. In addition, the percentage of delphinidin, peonidin and flavonoids in relation to the total anthocyanin content were similar between inner and peripheral fruits, suggesting that temperature may have little effect on anthocyanin synthesis in the superior strain. We concluded that the superior strain of ‘Tarocco’ blood orange has higher anthocyanin content than that the common variety and contains more kinds of metabolites. This study can provide a theoretical basis for genetic improvement and utilization of ‘Tarocco’ blood orange.

Key words: ‘Tarocco’ blood orange; superior strain; anthocyanin; liquid chromatography-tandem mass spectrometry